From 26df85d8bfb3c7c6d5b4d8d90485bff00fffc89d Mon Sep 17 00:00:00 2001
From: Tom Henderson <tomh@tomh.org>
Date: Mon, 13 Aug 2018 18:41:44 -0700
Subject: [PATCH] wifi: Document origin of formula

---
 src/wifi/model/wifi-phy.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/wifi/model/wifi-phy.cc b/src/wifi/model/wifi-phy.cc
index f006b46cb..b0a1adaf7 100644
--- a/src/wifi/model/wifi-phy.cc
+++ b/src/wifi/model/wifi-phy.cc
@@ -2150,6 +2150,8 @@ WifiPhy::GetPayloadDuration (uint32_t size, WifiTxVector txVector, uint16_t freq
   else if (mpdutype == NORMAL_MPDU && preamble != WIFI_PREAMBLE_NONE)
     {
       //Not an A-MPDU
+      // The number of OFDM symbols in the data field when BCC encoding 
+      // is used is given in equation 19-32 of the IEEE 802.11-2016 standard.
       numSymbols = lrint (stbc * ceil ((16 + size * 8.0 + 6.0 * Nes) / (stbc * numDataBitsPerSymbol)));
     }
   else